Update pin-8.md #393
Update pin-8.md #393
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The sentence ending in "…to achieve a stable." seemed off and prompted me to look into it. After a bit of reading, made a few changes, which i'm submitting here. Also, "the UART pins are useful" --> "can be useful": setting up over SSH is also an option here, and i think it's better not to make it sound like UART pins are the main option.
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Thank you- good catch, however: IIRC the default UART on Pi 3 and 4 is the miniUART, while the full-blown-hardware-UART is used for Bluetooth. The Using miniUART serial kinda works, but in my experience you can't rely on the baudrate to be at all consistent, so anything sensitive to UART stability - flashing a Parallax Propeller or reading a PMS5003 sensor - just goes awry. The consequence is- in theory- that Bluetooth will now be unstable and unreliable using this overlay, but if a user doesn't plan to use Bluetooth that's academic. |
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To be honest, i'm flying a bit by the seat of my pants here, as i didn't know what UART was before today. Apparently, when using miniUART the baudrate becomes dependent on the CPU speed, which varies, and so the whole thing becomes unreliable. I also so that this would require an update to pin-10.md to use the same wording, and more probably to uart.md, where some of this could (should ?) live. If you want to sort out the language here, i'm happy to update my PR to reflect that. Let me know what's the best way to proceed :) |
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As good a time as any to learn! Go for it. And thank you! |
Yup, and that's exactly what the |
src/en/pin/pin-8.md
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| UART can be used to talk to Serial GPS modules or sensors such as the PM5003, but you must make sure you disable the Serial Console in raspi-config first. | ||
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| On the Pi 3 and 4 the UART is, by default, used for Bluetooth and you may need to add "dtoverlay=miniuart-bt" to "/boot/config.txt" to achieve a stable. | ||
| On the Pi 3 and 4 the UART is, by default, used for Bluetooth and you may need to add "dtoverlay=miniuart-bt" to "/boot/config.txt" to be able to use UART (although a reduced version, mini UART). |
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Ah the pitfall of mentioning any specific Pi... the list is getting too darn long!
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Gotta admit... I'm not quite sure how to move forward with this one, but anything is preferable to a sentence that ends "to achieve a stable." I mean, what is this? A manual for building horse accommodation!? I think the direction I was going in was "to achieve a stable UART connection" or similar, since the default miniUART is... anything but. FWIW I think serial terminals deal okay with this, though? Normally seems to be a problem when using finicky serial devices like the aforementioned PMS5003. Perhaps something like: But then that's... incomplete. Documentation is tricky! |
Using @Gadgetoid's wording and explanations.
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@Gadgetoid ah ha, tricky, indeed. I've tried a rewording based on this conversation and your suggestion. Let me know. |
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LGTM. On the subject of UART documentation being tricky, the RPi docs page that this file links to is currently in the process of being updated too 🙂 |
I guess this is pretty good timing and we should maybe probably link to the official documentation too? |
Umm, you already do?! 😂 |
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In my defence I have a streaming cold and all my network hardware is strewn across the living room floor (boiler replacement) so I didn't even double check 😆 |
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Get well soon! 🤧 |
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Unless i'm missing something, i think this is ready to be merged? :) |
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| This pin doubles up as the UART transmit pin, TX. It's also commonly known as "Serial" and, by default, will output a Console from your Pi that, with a suitable Serial cable, you can use to control your Pi via the command-line. | |||
| This pin doubles up as the UART transmit pin, TX. It's also commonly known as "Serial" and, by default, will output a Console from your Pi that, with a [suitable Serial cable](https://elinux.org/RPi_Serial_Connection), you can use to control your Pi via the command line. | |||
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I think this might not actually be the default behaviour any more (because it requires setting the SoC to a fixed clockspeed, rather than letting it turbo on demand), and you need to explicitly request this functionality using raspi-config?
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Is that so? I don't mind lying temporarily to get this merged, and then figuring this out after the fact.
I uh... have been very, very deep in RP2040 lately so my Pi know-how is rusty.
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Is that so? I don't mind lying temporarily to get this merged, and then figuring this out after the fact.
See https://www.raspberrypi.com/documentation/computers/configuration.html#interfacing-options and https://www.raspberrypi.com/documentation/computers/config_txt.html#enable_uart
(although this is often a moving target, and unfortunately the documentation isn't always kept up to date with the changes in Raspberry Pi OS)
I uh... have been very, very deep in RP2040 lately so my Pi know-how is rusty.
Nice! 😀
The sentence ending in "…to achieve a stable." seemed off and prompted me to look into it. After a bit of reading, made a few changes, which i'm submitting here.
Also, "the UART pins are useful" --> "can be useful": setting up over SSH is also an option here, and i think it's better not to make it sound like UART pins are the main option.